The Mesozoic and Paleogene pelagic carbonate rocks of the Northern Apennines have proved to be a fertile source for paleomagnetic research. Investigations of the magnetic properties of the Scaglia limestones illuminated the processes by which they were magnetized. Their directions of remanent magnetization contributed to an understanding of the geodynamic history of Adria as a promontory of the African plate and have been used to refine the Mesozoic part of the African polar wander path. Magnetic stratigraphy in the Umbrian sequence and in similar facies in the southern Alps has established an independent record of geomagnetic polarity history since the Middle Jurassic. Correlation with the record derived from interpretation of oceanic magnetic anomalies mutually confirmed the global nature of the polarity history. This enabled the dating of plate motions and the development of a geomagnetic polarity time scale for the late Mesozoic and Cenozoic.

The regional-scale salients and recesses in the Appalachian orogen are well accepted as being a product of tectonic inheritance. Smaller map-view curves are present in the slate belt of the Taconic allochthon, which lies between the New York recess and Quebec salient, and we investigate the possibility that these curves are also related to the geometry of the preexisting Iapetan rift margin. The orientation of the slaty cleavage (S 2 ) and mineral/stretching lineation (L 2 ) and the geometry of syntectonic fibers were used to identify along-strike differences in the nature of the main stage of deformation (D 2 ) in the slate belt. Where the axial traces of F 2 folds lie parallel to the overall trend of the Taconic allochthon, the strata are characterized by an approximately downdip L 2 , plane strain, monoclinic strain symmetry, and top-to-west-northwest noncoaxial flow. The strata also underwent noncoaxial flow where the axial traces of F 2 folds are oblique to the overall trend of the Taconic allochthon. However, L 2 rakes moderately from the south on S 2 , and syntectonic fibers record evidence for flattening strain, triclinic strain symmetry, top-to-northwest shear in the XZ plane, and sinistral shear in the XY plane. We infer that the deformation zone in which D 2 structures formed changed orientation along strike such that the region of obliquely oriented F 2 folds underwent transpression, and we suggest that the transpressional deformation was a result of reactivation of a northwest-striking Iapetan transform fault as an oblique ramp during the Taconic orogeny.